OK so I'm considering becoming a vampire in Skyrim, (mainly because I was attacked by some and I think I got the disease, and I also wanna see what it's like :P) but I have a few questions.
1) Will other vampires attack me?
2) What are the benefits?
3) Is it difficult to feed?
4) (Most important question) Is it worth is?

1 Answer
1

Not really. Just feed on sleeping NPCs. You can even feed on your own followers (order them to sleep in a bed and feed on them before they stand up again). See more NPCs that can be easily fed upon at the UESP wiki's "Vampirism - Feeding" article.

The most effective and safe way to feed is merely using the Illusion spell "Invisibility" (the "Quiet Casting" Illusion perk would help too). While using Invisibility there are a few actions which do not interrupt and cancel the spell; feeding is one of these actions. Merely cast it and you are free to feed on any sleeping NPC without being seen, as long as the spell doesn't end in the middle of your feed.